EP4333116A1 - Method for manufacturing carbon-silicon composite powder, carbon-silicon composite powder manufactured thereby, and lithium secondary battery comprising same - Google Patents

Method for manufacturing carbon-silicon composite powder, carbon-silicon composite powder manufactured thereby, and lithium secondary battery comprising same Download PDF

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Publication number
EP4333116A1
EP4333116A1 EP22796076.2A EP22796076A EP4333116A1 EP 4333116 A1 EP4333116 A1 EP 4333116A1 EP 22796076 A EP22796076 A EP 22796076A EP 4333116 A1 EP4333116 A1 EP 4333116A1
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Prior art keywords
carbon
composite powder
silicon
mixed solution
prepare
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German (de)
English (en)
French (fr)
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Huijin KIM
Hyunki Park
Jungsu Park
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Grapsil Co Ltd
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Grapsil Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/20—Graphite
    • C01B32/21—After-treatment
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/02—Silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/01—Particle morphology depicted by an image
    • C01P2004/03—Particle morphology depicted by an image obtained by SEM
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/80—Particles consisting of a mixture of two or more inorganic phases
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to a method of preparing a high-capacity carbon-silicon composite powder with excellent conductivity, a carbon-silicon composite powder produced using the same, and a lithium secondary battery with excellent lifespan characteristics, output characteristics, and safety, including the carbon-silicon composite powder as an anode active material.
  • Lithium secondary batteries are widely used as power sources for mobile electronic devices including mobile phones and application fields thereof are expanding in response to increasing demand for large devices such as electric vehicles.
  • lithium secondary batteries use a carbon-based material as an anode active material, but attempts have recently been made to use metal materials such as Si, Sn, and Al that exhibit higher capacities as materials that can replace carbon-based anode active materials.
  • metal materials such as Si, Sn, and Al that exhibit higher capacities as materials that can replace carbon-based anode active materials.
  • these metal materials cause great volume expansion and contraction during lithium intercalation and deintercalation, disadvantageously resulting in undifferentiation, loss of conduction path, and the like, and thus deterioration in overall battery performance.
  • the present invention has made to overcome the drawbacks and disadvantages of the prior art and technical problems that have yet to be resolved in the art.
  • the silicon particles may have an average particle diameter (D50) of 10 nm to 1,000 nm.
  • a weight ratio of the silicon particles to the dispersion medium may be 1:99 to 30:70.
  • the spray drying may be performed at 50 to 300°C.
  • a weight ratio of the first composite powder to the carbon fibers in the second mixed solution may be 70:30 to 99.9:0.1.
  • a weight ratio of the first composite powder to the aqueous solvent containing carbon fibers may be 1:1 to 1:2.
  • the second mixed solution may contain a dispersant to disperse the first composite powder in an amount of 0.01 to 1% by weight based on the total weight of the first composite powder.
  • the cold isostatic pressing may be performed by injecting the second mixed solution into a container formed of rubber and then applying an isostatic pressure of 50 to 2,500 atm thereto using a cold isostatic press.
  • Drying may be performed at 70 to 300°C after the cold isostatic pressing (CIP).
  • CIP cold isostatic pressing
  • the carbon-silicon composite powder may have a porosity of 0.1 to 5%.
  • the carbon-silicon composite powder may have a spherical shape.
  • the carbon-silicon composite powder may have D90 of 20 ⁇ m to 80 ⁇ m.
  • a carbon-silicon composite powder prepared using the method.
  • an anode active material including the carbon-silicon composite powder.
  • a lithium secondary battery including the anode active material.
  • a carbon-silicon composite powder the shape of which is maintained without pulverization and that exhibits excellent process reactivity by preventing a carbon material and silicon particles from lumping in the process of preparing a carbon-silicon composite powder, thereby providing a lithium secondary battery with improved lifespan and output characteristics using the same.
  • the carbon-silicon composite powder prepared according to the present invention is compressed to minimize voids, and thus effectively blocks contact between the silicon particles and the electrolyte solution, thereby imparting safety to lithium secondary batteries.
  • the present invention provides a method of preparing a carbon-silicon composite powder including:
  • a carbon-silicon composite powder that retains a spherical or substantially spherical shape and thus has a predetermined particle diameter without pulverization by preventing the carbon material and silicon particles from lumping in the process of preparing the carbon-silicon composite powder, thereby providing excellent reaction fairness.
  • a lithium secondary battery using such a carbon-silicon composite powder as an anode active material effectively exhibits high-capacity silicon characteristics and alleviates volume expansion problems during charge and discharge, thereby improving lifespan and output characteristics.
  • the first mixed solution may be prepared by adding crystalline carbon and the precursor of amorphous carbon to the silicon slurry.
  • the silicon slurry may be separately prepared by thoroughly dispersing the silicon particles in a dispersion medium before mixing the crystalline carbon and the precursor of amorphous carbon. At this time, the silicon particles are used as a slurry without exposure to the atmosphere, thus suppressing oxidation. For this purpose, the capacity of the used lithium secondary battery may be further improved.
  • the silicon particles may have an average particle diameter (D50) of 10 nm to 1,000 nm.
  • D50 average particle diameter
  • the average particle diameter (D50) of the silicon particles is smaller than the lower limit of the range, process efficiency is reduced, and when the average particle diameter is larger than the upper limit of the range, micronization, contact with the electrolyte solution, or the like may occur during charge and discharge.
  • the average particle diameter may be 50 nm to 300 nm.
  • the average particle diameter (D50) of the silicon particles means a particle size at 50% of the particles in the cumulative distribution curve depending on the size of the particles.
  • D90 means a particle size at 90% of the particles in the cumulative distribution curve of the particles.
  • the dispersion medium may, for example, include one selected from the group consisting of N-methyl-2-pyrrolidone (NMP), tetrahydrofuran (THF), water, ethanol, methanol, cyclohexanol, cyclohexanone, methyl ethyl ketone, acetone, ethylene glycol, octyne, diethyl carbonate, dimethyl sulfoxide (DMSO), and combinations thereof, but is not limited thereto.
  • NMP N-methyl-2-pyrrolidone
  • THF tetrahydrofuran
  • water ethanol
  • methanol cyclohexanol
  • cyclohexanone cyclohexanone
  • methyl ethyl ketone methyl ethyl ketone
  • acetone ethylene glycol
  • octyne diethyl carbonate
  • DMSO dimethyl sulfoxide
  • the weight ratio of the silicon particles to the dispersion medium may be 1:99 to 30:70. When the weight ratio does not fall within the range defined above, disadvantageously, silicon particles or the like agglomerate into lumps or uniform dispersion of silicon particles in the dispersion medium is difficult. Specifically, the weight ratio of the silicon particles to the dispersion medium may be 5:95 to 20:80.
  • the first mixed solution may be prepared by adding crystalline carbon and a precursor of amorphous carbon to the silicon slurry such that the weight ratio of the silicon particles, the crystalline carbon, and the precursor of amorphous carbon is 20 to 70:20 to 70:1 to 19.
  • the crystalline carbon may be selected from the group consisting of natural graphite, artificial graphite, expanded graphite, graphene, fullerene soot and combinations thereof, but is not limited thereto.
  • the precursor of amorphous carbon may be dissolved in the dispersion medium of the silicon slurry, and there is no limitation as to the precursor as long as it is known in the art.
  • the precursor of amorphous carbon may include at least one selected from the group consisting of coal-based pitch, mesophase pitch, petroleum-based pitch, coal-based oil, petroleum heavy oils, organic synthetic pitch, phenol resins, furan resins, and polyimide resins.
  • the precursor of amorphous carbon is carbonized in the subsequent carbonization to form amorphous carbon.
  • the content of the precursor of amorphous carbon is excessively small, below the above range, it is difficult to provide appropriate strength and thus maintain the shape of the powder, and when the content of the precursor of amorphous carbon is excessively large, the powder may agglomerate due to the use of an adhesive during the preparation process, resulting in a prolonged pulverization process, conversion of the spherical powder into amorphous powder, and deterioration in the overall characteristics of the battery using the same.
  • the weight ratio of the silicon particles, crystalline carbon and the precursor of amorphous carbon in the first mixed solution may be 40 to 50:40 to 50:5 to 15.
  • the first composite powder may be prepared by spray drying the first mixed solution.
  • the spray drying may be performed by a general drying method including rotational spraying, nozzle spraying, ultrasonic spraying, or a combination thereof, and the flow rate of the solution during spraying, spraying pressure, spraying speed, temperature, or the like may be performed in an appropriate manner controlled depending on the average particle diameter of the first composite powder. Specifically, the spray drying may be performed at a temperature of 50 to 300°C.
  • a spherical first composite powder having an average particle diameter (D50) of 1 um to 100 um and a porosity of 20 to 40% may be obtained.
  • the second mixed solution may be prepared by adding the first composite powder to an aqueous solvent containing carbon fibers.
  • the carbon fibers may, for example, include at least one selected from carbon fibers, single-walled carbon nanotubes, multiwalled carbon nanotubes, carbon nanowires, and modified forms thereof, but are not limited thereto.
  • the aqueous solvent may, for example, include at least one selected from the group consisting of distilled water, methanol, ethanol, isopropyl alcohol, ethylene glycol, diethylene glycol, glycerol, and oleic acid, but is not limited thereto.
  • the second mixed solution may be prepared such that the weight ratio of the first composite powder to the carbon fibers is 70:30 to 99.9:0.1.
  • the content of the carbon fiber does not fall within the range defined above, disadvantageously, it is difficult to sufficiently secure electrical conductivity of the prepared carbon-silicon composite powder or processability may be deteriorated.
  • the second mixed solution may be prepared by adding the first composite powder to an aqueous solvent containing carbon fibers in a weight ratio of 1:1 to 1:2. Outside the above range, disadvantageously, the first composite powder cannot be sufficiently dispersed in an aqueous solvent containing carbon fibers.
  • a dispersant in order to effectively disperse the first composite powder, may be added in an amount of 0.01 to 1% by weight based on the total weight of the first composite powder.
  • the dispersant may be, for example, PVDF, stearic acid, resorcinol, polyvinyl alcohol, carbon pitch, or the like and may be first dispersed in an organic solvent such as NMP and then the result may be added to the second mixed solution.
  • the second composite powder may be prepared by performing cold isostatic pressing (CIP) on the second mixed solution, followed by drying.
  • CIP cold isostatic pressing
  • the cold isostatic pressing is a process of uniformly applying high pressure in all directions to a desired material using a liquid as a pressure medium.
  • the second mixed solution is sealed in a container made of rubber and is injected into a cold isostatic press, and the particles in the second mixed solution are pressed by applying an isostatic pressure of 50 to 2500 atmospheres (atm) thereto for 0.05 to 2 hours, followed by drying to prepare a second composite powder.
  • the pressure and temperature ranges should be determined so as to minimize the porosity of the second composite powder. When the pressure and temperature do not fall within the ranges, disadvantageously, desired effects cannot be obtained.
  • the liquid component is not wetted into the powder in the second mixed solution, so effective pressing is possible.
  • a second composite powder retaining the spherical shape can be prepared by drying at 70 to 300°C to remove residual solvent and the like after cold isostatic pressing (CIP) .
  • the carbon-silicon composite powder may be prepared by screening the spherical second composite powder without pulverization.
  • the carbon-silicon composite powder prepared according to the present invention is compressed to minimize voids, and thus is capable of effectively blocking contact between the active particles and the electrolyte solution, thereby ensuring the safety of a lithium secondary battery using the same.
  • the porosity of the carbon-silicon composite powder may be 0.1 to 5%.
  • the carbon-silicon composite powder prepared according to the present invention retains the spherical shape and minimizes agglomeration during the preparation process to prevent formation of lumps. Therefore, a powder having a desired size can be obtained only by a screening process without separate pulverization and thus preparation processability is excellent.
  • the screening may be performed using, for example, a 200 to 500 mesh sieve to remove a powder having a greater size than a predetermined size.
  • the D90 of the carbon-silicon composite powder is 20 um to 80 um, thus causing almost no a powder with a size less than 1 um and preventing deterioration in cell efficiency.
  • the present invention provides a carbon-silicon composite powder prepared using the method and an anode active material including the same.
  • the present invention provides a lithium secondary battery including the anode active material.
  • the lithium secondary battery includes a cathode including a cathode active material, an anode including the anode active material, and an electrolyte solution.
  • the cathode is formed by applying a cathode mix including the cathode active material to a current collector, and the cathode mix may further include a binder and a conductive material, if necessary.
  • the cathode active material may be, for example, a lithium metal oxide such as LiNi 0.8-x Co 0.2 AlxO 2 , LiCo x Mn y O 2 , LiNi x Co y O 2 , LiNi x Mn y O 2 , LiNi x Co y Mn z O 2 , LiCoO 2 , LiNiO 2 , LiMnO 2 , LiFePO 4 , LiCoPO 4 , LiMnPO 4 and Li 4 Ti 5 O 12 (0 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 1), chalcogenides such as Cu 2 Mo 6 S 8 , FeS, CoS, and MiS, oxides, sulfides or halides of scandium, ruthenium, titanium, vanadium, molybdenum, chromium, manganese, iron, cobalt, nickel, copper and zinc, and the like.
  • chalcogenides such as Cu 2 Mo 6 S 8 , FeS, CoS, and Mi
  • the cathode active material may be LiNi 0.8 Co 0.1 Mn 0.1 O 2 , TiS 2 , ZrS 2 , RuO 2 , Co 3 O 4 , Mo 6 S 8 , V 2 O 5 , or the like, but is not limited thereto.
  • the shape of the cathode active material is not particularly limited and may be a particle shape, such as a spherical shape, an elliptical shape, or a rectangular parallelepiped shape.
  • the average particle diameter of the cathode active material may be in the range of 1 to 50 um, but is not limited thereto.
  • the average particle diameter of the cathode active material may be obtained by, for example, measuring the particle diameters of the active material observed with a scanning electron microscope and calculating an average thereof.
  • the binder is not particularly limited and may be a fluorine-containing binder such as polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE), but is not limited thereto.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • the content of the binder is not particularly limited as long as the cathode active material can be fixed, and may be in the range of 0 to 10% by weight with respect to the total weight of the cathode.
  • the conductive material is not particularly limited as long as the conductivity of the cathode can be improved and examples thereof include nickel powder, cobalt oxide, titanium oxide, and carbon.
  • the carbon may include at least one selected from the group consisting of Ketjen black, acetylene black, furnace black, graphite, carbon fiber, and fullerene.
  • the content of the conductive material may be determined in consideration of other battery conditions such as the type of conductive material, and may be, for example, in the range of 1 to 10% by weight with respect to the total weight of the cathode.
  • the thickness of the cathode mix layer obtained by applying the cathode mixture including the cathode active material, the binder, and the conductive material to the current collector may be, for example, 0.1 micrometers to 1,000 micrometers.
  • the cathode mix may include the solid electrolyte according to the present invention in an amount of 0.1% to 60% by weight, specifically 10% to 50% by weight, based on the total weight of the cathode mix.
  • the thickness of the cathode mix layer may be, for example, 0.1 micrometers to 1,000 micrometers.
  • the cathode current collector there is no particular limit as to the cathode current collector, so long as it has high conductivity without causing adverse chemical changes in the fabricated battery.
  • the cathode current collector include stainless steel, aluminum, nickel, titanium, sintered carbon, and aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver or the like.
  • the current collector may be used in various forms including films, sheets, foils, nets, porous structures, foams and non-woven fabrics having fine irregularities on the surface thereof.
  • the anode is formed by applying an anode mix including the anode active material to an anode current collector.
  • the anode active material may be the anode active material according to the present invention, but may be used in combination with metal oxide, a metal, lithium composite oxide, crystalline carbon, amorphous carbon, or the like.
  • the anode mix may further include a binder and a conductive material having the configuration as described above.
  • the anode current collector there is no particular limit as to the anode current collector, so long as it has high conductivity without causing adverse chemical changes in the fabricated lithium secondary battery.
  • the anode current collector include copper, stainless steel, aluminum, nickel, titanium, sintered carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, or the like, aluminum-cadmium alloys and the like.
  • the anode current collector may be used in any one of various forms selected from films, sheets, foils, nets, porous structures, foams and non-woven fabrics having fine irregularities on the surface thereof.
  • the electrolyte solution contains an organic solvent and an electrolyte.
  • any one may be used as the organic solvent without limitation as long as it is commonly used and examples thereof include propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, dipropyl carbonate, dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, vinylene carbonate, sulfolane, gamma-butyrolactone, propylene sulfite, tetrahydrofuran and combinations thereof.
  • any commonly used lithium salt may be used without limitation as the lithium salt that may be contained in the electrolyte and examples of the anion may include at least one selected from the group consisting of F-, Cl-, I-, NO 3- , N(CN) 2- , BF 4- , ClO 4- , PF 6- , (CF 3 ) 2 PF 4- , (CF 3 ) 3 PF 3- , (CF 3 ) 4 PF 2- , (CF 3 ) 5 PF-, (CF 3 ) 6 P - , CF 3 SO 3- , CF 3 CF 2 SO 3- , (CF 3 SO 2 ) 2 N - , (FSO 2 ) 2 N - , CF 3 CF 2 (CF 3 ) 2 CO - , (CF 3 SO 2 ) 2 CH - , (SF 5 ) 3 C - , (CF 3 SO 2 ) 3 C - , CF 3 (CF 2 ) 7 SO 3- , CF 3 CO 2- , CH 3 CO 2- , S
  • a separator is disposed between an anode and a cathode to form a battery structure, the battery structure is wound or folded and accommodated in a cylindrical battery case or a prismatic battery case, and then an electrolyte is injected to complete a secondary battery.
  • a battery structure having a bi-cell structure is stacked and impregnated with an electrolyte, and the resulting structure is sealed in a pouch to complete a lithium secondary battery.
  • a silicon slurry was prepared by mixing 10% by weight of Si with 90% by weight of ethanol.
  • the size (D50) of the silicon was 105 nm.
  • the graphite used herein had a D50 of 3 um.
  • the pitch used herein had a D50 of 5 ⁇ m.
  • the first mixed solution was dried at 80 to 150°C using a spray dryer to prepare a spherical first composite powder.
  • the prepared spherical first composite powder had a size (D50) of 11 ⁇ m.
  • the prepared spherical first composite powder was mixed with a solvent containing 0.1 wt% of CNTs having a length of 5 to 15 um to prepare a second mixed solution.
  • the CNT concentration is a ratio with respect to the mixed powder.
  • the weight ratio of the spherical first composite powder to the solvent is 1:1 to 1:1.5.
  • a dispersion of PVDF in NMP was added as a dispersant to the solvent.
  • the amount of PVDF was 0.1% by weight of the spherical first composite powder.
  • the solvent was prepared by mixing water with ethanol in a weight ratio of 8:2.
  • the solvent and powder of the second mixed solution were mixed using a rolling mixer for about 2 hours, added to a rubber tube and sealed.
  • the rubber tube was put into a CIP compressor chamber and compressed at a predetermined pressure. At this time, the pressure was 100 atm for 0.1 hours.
  • the solvent was removed using a centrifugal separator, dried at 100°C to prepare a second composite powder, and then screened using a 400 mesh sieve to remove more than 90% of the powder with a size of about 30 um or more to prepare a carbon-silicon composite powder.
  • a carbon-silicon composite powder was prepared in the same manner as in Example 1, except that the CIP process was performed at 200 atm.
  • a carbon-silicon composite powder was prepared in the same manner as in Example 1, except that 0.1% by weight of polyvinylpyrrolidone (PVP) was added to the spherical first composite powder in a solvent and the CIP process was performed at 200 atm.
  • PVP polyvinylpyrrolidone
  • a carbon-silicon composite powder was prepared in the same manner as in Example 1, except that pressing using the CIP process was not performed.
  • the carbon-silicon composite powder according to Example 1 maintains a spherical powder shape, whereas the shape of the carbon-silicon composite powder according to Comparative Example 1 is substantially amorphous, and a large amount of powder with a size of 1 um or less is observed.
  • the porosity inside the non-compressed powder of Comparative Example 2 was 35%, and the porosity in the compressed powder of Example 1 was 1% or less.
  • the anode plate was designed by setting the rolling density to 1.58 g/cc, the current density to 2.8 mA/cm 2 , and the electrode capacity to 485 mAh/g.
  • a porous polyethylene separator was interposed between the cathode and the anode, and an electrolyte prepared by dissolving 1M LiPF 6 in a solution of 0.5 wt% vinylene carbonate in a mixed solution containing methyl ethyl carbonate (EMC) and ethylene carbonate (EC) mixed at a ratio of 7:3 was inserted to produce a lithium coin half-cell.
  • EMC methyl ethyl carbonate
  • EC ethylene carbonate
  • the lithium coin half-cell was tested under the conditions of single efficiency: 0.1C/0.1C, 50 cycles, and lifespan: 1.0C/1.0C, 50 cycles.
  • the basic charge and discharge conditions are as follows.
  • Table 1 shows the single efficacy and the lifespan after 50 cycles of the lithium coin half cells according to Examples 1 to 3 and Comparative Example 1.
  • the residual capacity rates of the lithium coin half cells according to Example 1 and Comparative Example 2 as a function of the number of cycles is shown in FIG. 3 .
  • Examples 1 to 3 exhibit excellent initial efficiency and 50 cycle lifespan compared to Comparative Example 1. This is because the carbon-silicon composite powder according to Comparative Example 1 is substantially amorphous and includes a large amount of powder having a size of 1 um or less, which reduces battery efficiency when applied to the anode. In addition, as can be seen from FIG. 3 , Example 1 undergoing pressing exhibits a high residual capacity as a function of the number of cycles, compared to Comparative Example 2 not undergoing pressing.

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EP22796076.2A 2021-04-28 2022-04-25 Method for manufacturing carbon-silicon composite powder, carbon-silicon composite powder manufactured thereby, and lithium secondary battery comprising same Pending EP4333116A1 (en)

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PCT/KR2022/005879 WO2022231243A1 (ko) 2021-04-28 2022-04-25 탄소-실리콘 복합체 분말의 제조 방법, 이에 의하여 제조된 탄소-실리콘 복합체 분말 및 이를 포함하는 리튬 이차전지

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KR102508088B1 (ko) * 2022-01-25 2023-03-10 주식회사 레몬에너지 이중층 구조의 실리콘 카본 복합체 음극활물질, 그 제조방법 및 이를 포함하는 이차전지
KR20240063564A (ko) * 2022-11-03 2024-05-10 삼성에스디아이 주식회사 리튬 이차 전지용 음극 활물질, 이를 포함하는 음극 및 이를 포함하는 리튬 이차 전지

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KR102244226B1 (ko) * 2019-10-22 2021-04-26 주식회사 그랩실 도전성 섬유에 의한 네트워크에 의해 형성된 실리콘 복합체를 포함하는 음극 활물질, 이의 제조방법 및 이를 포함하는 리튬 이차전지

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